Alan (pronounced ah-lahn), a Tibetan, Chinese-born Buddhist, has only two Japanese albums under her belt, and neither are masterpieces. She appears on this list because she's unlike any other mainstream pop starlet currently working, and has an abundance of only periodically realised potential. Sound strange? I'll try to explain.

Her musical stylings, on the surface, are nothing especially remarkable – largely sugary, innocuous piano ballads that you could expect to hear in an unassuming Chinatown gift shop because the 70-year- old shopowner finds it soothing. But every few tracks (including her Nipponese debut single, the gorgeous Ashita e No Sanka), Alan employs one or both of her secret weapons: her chillingly ancient-sounding "Tibetan wail", and her ability to play the erhu. Those would be, respectively, a singing technique wherein the vocals are extensively held at a high-pitched waver, and the mournful Chinese string instrument you've probably heard on the soundtrack to any martial arts movie ever made. Even the briefest appearances of either transforms Alan's music into genuinely beautiful, ethereal mood pieces that are more moving and substantial than the vast majority of mass-marketed pop ballads.

As well as Ashita e No Sanka, she's worth hearing for Red Cliff, the theme song to the Chinese drama of the same name – available in both a Chinese and a Japanese version – and the subtly pretty Together, which is the first song for which she composed the music. She still has a way to go before perfecting her signature style, but she's more than worth watching along the way.

Nana Kitade is a bit of a mystery. After releasing her most recent album, 2009's exceptional Bondage, her contract with Sony expired and fans were left with a note from the company stating that Kitade was on hiatus owing to health problems. Now she's announced she will be fronting a band called Loveless. So far they don't appear to have a label, and have been performing live shows around Tokyo instead. It is not easy to find out any more about the band than that. Low sales might be the real reason Sony didn't renew Kitade's contract, but it's hard to believe there's no place in Japan's mass market for her mischievous blend of pop-rock or her unique image. Not to mention that almost every one of her singles has been the theme song for an anime, videogame, or TV drama. Isn't that enough to warrant some good faith?

Kitade is perhaps best known for her Lolita style of dress, something she adopted after her first album but seems to have now ditched. Lolita is an incredibly elaborate fashion fad in Tokyo, wherein the wearer dons layers of frilly dresses, bonnets and parasols until they resemble some sort of rococo porcelain doll version of Little Bo Beep – a wonderful contrast to Kitade's bratty, punky music. Now with Loveless, judging by the website photos, she's let go of the "cute" component altogether. With Kitade sporting teased hair, dark, smudged makeup, ropes and an arm piercing, it's safe to assume her music will also take a turn for the darker. Without a label to influence her or sales to worry about, it will be interesting to see what kind of rawer, badder music she might be performing live these days (the inclusion of a cover of Nirvana's Territorial Pissings on Loveless's setlist makes this question all the more interesting). We can only hope that some of it hits the shelves soon, and that she doesn't disappear completely. Here's to her health.

Tomoko Kawase has been the frontwoman of pop-rock trio the Brilliant Green for 10 years, with two impressive solo projects running alongside. The first was Tommy February6, a sugary synth-loving alter ego in which Kawase put on wire-frame glasses and played up an innocent, adolescent image – bright colours and cheerleading outfits included. Following that came the superior Tommy Heavenly6, for which she adopted a goth-lite style and made rollicking 90s-style alt-rock. The number of Japanese females successful in three different musical outfits is paltry, which makes Kawase (technically now Mrs Okuda after marrying her Brilliant Green bandmate Shunsaku Okuda) so remarkable.

In all three acts, Kawase sings in an enticingly awkward mishmash of English and Japanese, sometimes starting a sentence in one language and finishing it in the other. This practice isn't uncommon in J-Pop, but it's usually used more sparingly. To her credit, though, Kawase has a better handle on the pronunciation than most, and could do well in the western indie scene, were she inclined to test the waters. She also knows a good turn of phrase – witess Tommy Heavenly6's song My Bloody Knee-High Socks. The only one of these three identities that's still going is the Brilliant Green. As good as the band is, it's a shame that's her only current outlet. Luckily for the uninitiated, there are 10 albums of Kawase goodness.

She may be declining in popularity, relevance and quality, but Ayumi Hamasaki is still the undisputed Queen of J-Pop, and it will be a long while before anyone can surpass her. She is as famous in Japan as Madonna is in the west – her face is plastered all over Tokyo. She's a chameleonic style icon whose innocent pop-princess image has never taken a turn for the oversexed, though she's often used cosmetic surgery. Musically, she has married accessible, mainstream hits with over-the-top costumes and high-concept videos long before Lady Gaga did. And most of the time her music is very good.

Hamasaki's lyrics and delivery – she has an earnest, unpolished singing voice – project a vulnerability that makes her songs strangely endearing and her ballads occasionally touching. My favourite song of Ayumi's is Ladies Night, a hymn to girl power. The lyrics encourage a friend to leave an abusive relationship – not a common pop theme. That willingness to address unusual subject matter makes her noteworthy. I hope she doesn't change.

Shiina Ringo has been a significant influence on at least two of the singers on this list, and consistently ranks high in Japanese polls for favourite artists. Her popularity through the years, even though she's taken extended breaks from music, speaks volumes of the rabid love she inspires in her fans. This, naturally, includes me. She is my favourite Japanese artist, and I sometimes think she might be my favourite artist anywhere. Before forming the band Tokyo Jihen in 2004, Ringo released three solo albums, each better than the last.

The third, Karuki Zamen Kuri No Hana (2003) is her masterpiece. Layered with complex sounds and tempo switch-ups, it's an album that demands and rewards multiple listens.

It would have been hard to top, so it's understandable that she turned her focus to her band for the next few years before releasing her fourth solo album (with composer Saito Neko in tow), 2007's Heisei Fuuzoku.

Its songs were used in and inspired by the movie Sakuran, and featured updated reworkings of a few of her older tracks. While it doesn't match her other three solo efforts, it had some memorable moments, and contained what might be her best song yet, Gamble.

Sanmon Gossip, released last year, is probably her lightest album, and she finally consummates her relationship with the loungey jazz she's been flirting with for years. All but absent are the hard-rocking, thrashy, catchy melodies for which she's known. Togatta Teguch comes closest to her former style and provides a reminder of past glories. While I'm not the biggest fan of her jazz-piano departure, musicians reinvent themselves,and I'm too ecstatic that she's still making music to quibble.

How do you move on from being Dublin's rock'n'roll Lucifer? By becoming U2's 'aesthetic midwife', outdressing 50 Cent and roping in the Salvation Army for your latest album. Mike Atkinson meets Gavin Friday